Photooxygenation of a microbial arene oxidation product and regioselective Kornblum-DeLamare rearrangement: Total synthesis of zeylenols and zeylenones

We report the enantioselective total syntheses of zeylenol (+)-1, as well as its congeners (-)-7 and 16, and of 3-O-debenzoylzeylenone 28. To this end, a new variant of the Kornblum-DeLaMare rearrangement, which utilises neighbouring-group participation to impart regioselectivity, has been developed. The approach employs photooxygenation of building blocks derived from a microbial arene oxidation product. New light on a Korny rearrangement: Biooxidation of benzoic acid with R. eutrophus B9 gives a dearomatised diene diol acid that allows concise access to the zeylenol and zeylenone family of polyoxygenated cyclohexene natural products. The synthesis employs diene photooxygenation and a new regioselective variant of the Kornblum-DeLaMare endoperoxide fragmentation has been developed (see scheme).